The strongest cleaner that is pH neutral and completely safe is the SONAX Wheel Cleaner Full Effect. It's really amazing and many detailers are using it on exotic wheels. Check out this article with pictures of it in action:

^^^ sonax is the shnizzel!!! i bought 4 bottles from greg and joe got one of those bottles. he loves it on his srt. melts that brake dust like nothing! i also use poorboys wheel sealant or optimum opti seal on my rims to seal. also sold at detailedimage lol